The stricken Costa Allegra has been forced to change course and head for the main Seychelles island of Mahe after it was deemed too risky for passengers to disembark at the smaller Desroches Island.

Passengers and crew on board the cruise liner, which is being towed after losing all power, face the prospect of a weary few days on board as the ship has no air-conditioning or cooking facilities.

A statement from Costa Cruises, which owns the Costa Allegra as well as the ill-fated Costa Concordia, said that Desroches was considered too small to be able to accommodate the 1000 passengers and crew and that the ship would be too big for the dock on the luxury island resort. Passengers will now arrive at the Seychelles' capital, Victoria, on Thursday.

Torches and "comfort items" for the people still on board are expected to be provided by helicopter, the Costa Cruises statement continued. The 28,597 gross tonne ship has armed security on board and fears that it could be targeted by Somali pirates were played down.